Dealuminated zeolite Y in which the SiO.sub.2 /Al.sub.2 O.sub.3 ratio is greater than 20 is known as a pulverulent substance. It is produced by treating zeolite Y in the sodium or hydrogen form with silicon tetrachloride at temperatures from 450.degree. to 600.degree. C. (WO 88/03437--Zeol; Beyer et al., Catalysis by zeolites, pages 203 et seq. (1980) Elsevier). It has a pronounced hydrophobic character due to its specific SiO.sub.2 /Al.sub.2 O.sub.3 ratio and may therefore be used for the adsorption of organic compounds, for example solvents, from exhaust air and effluent.
The use of pulverulent dealuminated zeolite Y as adsorbent, for example in fixed bed adsorbers, has the disadvantage that owing to the high packing density an undesirably great pressure drop occurs in the fixed bed and hence a reduction in throughput. Difficulties also arise in a fluidised bed adsorber because the fine powder can only be transferred to the fluidised layer with difficulty. Another disadvantage is the large amount of dust produced when the zeolite powder is introduced into the fixed bed.